I’ve often cited Star Wars (Episode IV) as an example for why movies shouldn’t be adaptions. Lucas synthesized myriad influences into a new (yet not new) work that is a better film than all but a few direct adaptions. (And many of the better adaptions wandered far enough afield as to arguably not be adaptations.)
Likewise, I’m not a fan of intellectual property and especially any form of intellectual property that restricts adaptions. The execution means more than the idea. The “owner” of the original idea should have no claim on the execution—the hard work—of others; and the execution shouldn’t be restricted by the “owner” of the original idea.
But Lucas wanted to make a Flash Gordon film. He made Star Wars because he couldn’t get the rights.
So, ironically, my example of why you shouldn’t create an adaptation only exists because of intellection property rights.